Abstract
This study examined the dimensionality of morphological knowledge. The performance of 371 seventh- and eighth-graders on seven morphological knowledge tasks was investigated using confirmatory factor analysis. Results suggested that morphological knowledge was best fit by a bifactor model with a general factor of morphological knowledge and seven specific factors, representing tasks that tap different facets of morphological knowledge. Next, structural equation modelling was used to explore links to literacy outcomes. Results indicated the general factor and the specific factor of morphological meaning processing showed significant positive associations with reading comprehension and vocabulary. Also, the specific factor of generating morphologically related words showed significant positive associations with vocabulary, while specific factors of morphological word reading and spelling processing showed small negative relationships to reading comprehension and vocabulary. Findings highlight the complexity of morphological knowledge and suggest the importance of being cognizant of the nature of morphology when designing and interpreting studies.